http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Suppression of abnormal chattering of a high-speed EMU carbody
Dao Gong,Zegen Wang,Jinsong Zhou,Jianyue Zhu 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
A carbody chattering phenomenon accompanied by bogie hunting movement was investigated. The online test results showed that the vehicle at a large tread conicity state exhibited insufficient stability when running at higher speeds, causing the hunting frequency of the bogie to continuously increase, approach the diamond-shaped deformation modal frequency of the carbody, consequently causing the carbody to chatter. To improve the running stability of the vehicle, to suppress the carbody chattering, a two-step progressive optimisation method that combined analytical optimisation, simulation optimisation to optimise the parameters of the anti-yaw damper was proposed. Furthermore, the effect of optimisation was experimentally verified. Results showed that after optimisation, the critical speed of the vehicle under the condition of worn wheel was significantly enlarged, the bogie exhibited no obvious hunting motion, carbody chatter was significantly alleviated, both the ride quality, the curve passing performance were improved.
Passive control of railway vehicle car body flexural vibration by means of underframe dampers
Dao Gong,Jinsong Zhou,Wenjing Sun 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2
To suppress vertical flexural vibration of a railway vehicle car body, a new passive control method by mounting dampers on the longitudinal beams of the car body underframe is proposed. The method is firstly studied by an Euler-Bernoulli beam model using Green’s functions, then it is further verified by a nonlinear dynamic model of the vehicle. Results show that the car body flexural vibration can be noticeably reduced by this method. It is better to mount the damper near the car body centre. The higher damping coefficient of the damper, the more effective in decreasing the car body first vertical bending vibration. The higher the rigidity of the damper bracket and rubber bush, the better performance of the damper. It is found that when mounting six dampers at proper positions, the damping coefficient of each damper is 1.33×10 7 N·s/m, even if the first vertical bending frequency of the studied car body is only 7.2 Hz, a very good ride quality will be achieved when the vehicle runs at 250 km/h.
A modal frequency optimization approach for a fully-equipped car body of high-speed trains
Dao Gong,Zegen Wang,Guangyu Liu,Jinsong Zhou 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1
The tubular structural car body of high-speed trains with lightweight design generally results in a low diamond deformation modal frequency, which deteriorates significantly both the lateral and vertical vibrations of the car body. To increase the diamond deformation modal frequency of the car body, the structural optimization and modal sensitivity optimization of the car body based on sensitivity analysis are proposed. The former starts with the analysis of the mode shape deformation characteristics; in the latter case, the modal strain energy verification is considered and the influence of the threshold values of sensitivity on the modal frequency optimization are studied. Results show that by increasing the spacing of the inner and outer panels of the side wall from 47 mm to 65 mm and optimizing the thicknesses of 16 components of the car body, the diamond deformation modal frequency of the fully-equipped car body can be enhanced from 8.7 Hz to 10.31 Hz, while ensuring the lightweight requirement without loss in car body strength.
Gong Xiaowei,Luo Huajun,Hong Liu,Wu Jun,Wu Heng,Song Chunxia,Zhao Wei,Han Yi,Dao Ya,Zhang Xia,Zhu Donglai,Luo Yiyong 한국미생물학회 2022 The journal of microbiology Vol.60 No.8
Tryptophol (TOL) is a metabolic derivative of tryptophan (Trp) and shows pleiotropic effects in humans, plants and microbes. In this study, the effect of Trp and phenylalanine (Phe) on TOL production in Saccharomyces cerevisiae was determined, and a systematic interpretation of TOL accumulation was offered by transcriptomic and metabolomic analyses. Trp significantly promoted TOL production, but the output plateaued (231.02−266.31 mg/L) at Trp concentrations ≥ 0.6 g/L. In contrast, Phe reduced the stimulatory effect of Trp, which was strongly dependent on the Phe concentration. An integrated genomic, transcriptomic, and metabolomic analysis revealed that the effect of Trp and Phe on TOL production was mainly related to the transamination and decarboxylation of the Ehrlich pathway. Additionally, other genes, including thiamine regulon genes (this), the allantoin catabolic genes dal1, dal2, dal4, and the transcriptional activator gene aro80, may play important roles. These findings were partly supported by the fact that the thi4 gene was involved in TOL production, as shown by heterologous expression analysis. To the best of our knowledge, this novel biological function of thi4 in S. cerevisiae is reported here for the first time. Overall, our findings provide insights into the mechanism of TOL production, which will contribute to TOL production using metabolic engineering strategies.
Jinyan Gong,Dao-Zong Xia,Jun Huang,Qing Ge,Jian-wei Mao,Shiwang Liu,Ying Zhang 한국식품영양과학회 2015 Journal of medicinal food Vol.18 No.4
This study was designed to detect characteristic compounds and evaluate the free radical scavenging capacity of the bamboo leaves extract and bamboo shavings extract (BSE). The antioxidant capacity of bamboo leaf n-butanol fraction (AOB) exhibited the highest total phenolic content (49.93%), total flavonoids content (24.11%), and characteristic flavonoids and phenolic acids, such as chlorogenic acid, caffeic acid, ferulic acid, p-coumaric acid, orientin, homoorientin, vitexin, and isovitexin. Available data obtained with in vitro models suggested that AOB had higher free radical scavenging capacity with IC50 values of 1.04, 4.48, 5.37, and 1.12 μg/mL on DPPH•, O2•- , •OH, and H2O2, respectively, than the other two extracts, bamboo leaf water extract and BSE. The results indicated that the extracts from different parts of the bamboo possess excellent antioxidant activity, which can be used potentially as a readily accessible and valuable bioactive source of natural antioxidants.